Transient voltage suppressors are used in a variety of electrical systems to prevent high voltage transients from damaging system components. For example, computer systems connect transient voltage suppressors across data and/or power lines to dissipate the energy induced by a transient event such as a noise pulse, a static discharge, or a lightning strike. The transient suppressors break down when a transient voltage exceeds a predetermined level, thereby limiting the voltage on the data and power lines and avoiding component damage. A typical transient suppressor breaks down when a transient voltage exceeds eight volts and shunts at least one ampere of current which would otherwise flow through other system components and lead to a destructive failure of the system.
One type of transient voltage suppressor uses large Zener or avalanche diodes to dissipate the current associated with the transient event. A drawback with large Zener diodes is that they have a large capacitance which loads the data lines and slows down the data transfer rate. Another transient voltage suppressor comprises a device having a Zener region and a non-Zener region, where the Zener region controls the Zener voltage of the device. A drawback with this type of device is that the Zener region includes an NPN transistor that has a higher gain than the non-Zener region. During a surge, the current may be localized in the Zener region resulting in a local hot spot that degrades the device performance. The effects of the NPN transistor may be mitigated by increasing the size of the Zener region, however this introduces an undesirably high capacitance.
Accordingly, it would be advantageous to have a transient voltage suppressor device that includes a Zener region, a method for manufacturing the transient voltage suppressor device, and a method for handling the gain of the Zener region of a transient voltage suppressor device that do not introduce a large capacitance in the device. It would be of further advantage for the device and method to be cost efficient to manufacture.